Freemasonry is not bad. It is simply a social, educational, and charitable organization for men. Becoming a mason does not require that one belong to a specific religion, in fact arguments over religious differences are specifically forbidden. All it requires is that one have a belief in some Higher Power. Some Christian groups have given Masonry a bad rep because they don't like the fact that it is not specifically Christian. Heck, most of the Founding Fathers including George Washington were Freemasons.
You can find a ton of information on Freemasonry at http://web.mit.edu/dryfoo/masonry/